CXA1940N

CXA1940N 4ch. Read/Write Amplifier for Thin Film Head of Hard Disk Drive For the availability of this product, please contact the sales office. Description The CXA1940N is a Read/Write Amplifier for the thin film head of hard disk drives and designed to handle up to 4-channel heads. Features • Operate on single +5V power supply. • Low power consumption. Read : 95mW Write (IW=20mA) : 130mW+IW × 5 Power save : 5.5mW • Write current can be varied through an external resistor. Built-in stabilizing circuit provides stable current during voltage and temperature drift. • Drives up to 4 heads. • Designed for two-terminal thin-film or MIG heads. • Built-in power save function. • Read amplifier emitter follower output featuring 290 times gain (Typ.). • Built-in Write unsafe detection circuit. • Built-in supply voltage monitor circuit prohibits incorrect Write during power on or abnormal voltage. • Built-in IC protection circuit for short of head and GND. • Differential input capacitance for Read : 14pF (Typ.). • Write data input minimum pulse width : 10ns • Read data output become high impedance in write mode to improve read data offset when switching from write to read mode. • Unselected head DC voltage is GND potential. • Self switching damping resistance (RD=310Ω) 20 pin SSOP (Plastic) Block Diagram and Pin Configuration GND 1 DRIVER MODE CONTROL 20 PS H0X 2 19 R/W H0Y 3 AMP WRITE CURRENT SOURCE 18 WC DRIVER H1X 4 AMP 17 RDY H1Y 5 AMP 16 RDX DRIVER H2X 6 HEAD SELECT 15 HS0 H2Y 7 AMP 14 HS1 DRIVER H3X 8 POWER ON/OFF DETECTOR 13 VCC H3Y 9 AMP T-FF 12 WDI NC 10 IC PROTECTOR WRITE UNSAFE DETECTOR 11 WUS Sony reserves the right to change products and specifications without prior notice. This information does not convey any license by any implication or otherwise under any patents or other right. Application circuits shown, if any, are typical examples illustrating the operation of the devices. Sony cannot assume responsibility for any problems arising out of the use of these circuits. —1— E93X03-TE CXA1940N Structure Bipolar silicon monolithic IC Function Read, Write and Write unsafe detection for HDD, Power supply ON/OFF detection. Absolute Maximum Rating (Ta=25°C) • Supply voltage VCC • Write current IW • Operating temperature Topr • Storage temperature Tstg • Allowable power dissipation PD Recommended Operating Conditions • Supply voltage VCC • Write current IW 7 25 –20 to +75 –55 to +150 375 V mAo-p °C °C mW 5V±10 5 to 20 % mAo-p —2— CXA1940N Pin Description No. 1 2 3 4 5 6 7 8 9 10 Symbol GND H0X H0Y H1X H1Y H2X H2Y H3X H3Y NC VCC VCC Equivalent circuit Description 2 4 6 8 3 5 7 9 GND 2k 2k Head. 4 channels provided. 11 WUS 11 Write unsafe detection output. Open collector output. When it is off in Write mode, it means an error is detected. GND VCC 12 WDI 12 Write data input. At “High” → “Low”, input is triggered. 2.1V 1.4V GND 13 14 15 VCC HS1 HS0 14 VCC 19 R/W 15 19 20 PS 20 2.1V GND 5V power supply Head select signal input. Selects one of 4 heads according to Table 2. Read/Write signal input. At “High”: Read, at “Low”: Write. Power save signal input. At “High”: Power save. —3— CXA1940N No. Symbol Equivalent circuit VCC Description 16 17 RDX RDY 16 17 Read Amplifier output. GND VCC 18 WC 18 1.25V GND A setting resistor for the write current value is connected between this pin and GND. —4— CXA1940N Electrical Characteristics No. 1-1 1-2 1-3 2-1 2-2 2-3 2-4 3-1 3-2 Item Current consumption for Read Current consumption for Write Current consumption for Power save Digital input “Low” input voltage Digital input “High” input voltage Digital input “Low” input current Digital input “High” input current Write unsafe output saturation voltage Write unsafe output leak current (Unless otherwise specified, VCC=5V, Ta=25°C, Write current IW=20mA) Typ. Max. Unit 19 26 +IW 1.1 26 35 +IW 1.5 0.8 2.0 aa aaa aaa aa aa aa aaa bab ba bb “High” applied voltage : 5V “Low” applied voltage : 0V Test point : I3, I5, I6, I7, I8 SymSW Conditions bol 1 2 3 4 5 6 7 8 9 101112 Measurement conditions Min. Test point : I4 IR b a a a a b a a a a b a 12 IW IP VIL VIH IIL IIH ba aaa baa aa aa ba aaa baa aa bb Test point : I4 Test point : I4 Digital input : Pins 12, 14, 15, 19, 20 17 +IW 0.6 mA mA mA V V µA –20 70 0.5 20 µA V µA VWUS b a a a b c a a a a a a IWUS b a a a e c a a a a a a Output current : 1mA Test point : V1 Test point : I2 Supply power 4 ON/OFF detector threshold voltage VTH When VCC is lowered from 5V in Write mode and IW does not flow anymore, VCC voltage is 3.6 ba aaa baa aa aa set to VTHOFF. When VCC is raised from 3V and IW starts to flow, VCC voltage is set to VTHON. ba aaa baa aa aa 5 3.9 4.3 V Write current setting 5 range Write current IW 20 mAo-p 6 tolerance ∆Iw b a a a a b a a a a a a -8 8 % Read amplifier 7 differential voltage gain AV Input voltage SG1 : 1mVp-p, 300kHz Load resistance (RDX, ba aac baa ab ba RDY) : 1kΩ Test point : V4 [Vp-p] AV= V4 SG1 245 290 335 V/V Frequency 8 band width (–3dB) BW b a a a c b a a a b b a Frequency at which AV lowers by 3dB 30 MHz —5— CXA1940N No. Item 9 Input referred noise SymSW Conditions Measurement conditions Min. bol 1 2 3 4 5 6 7 8 9 101112 Head impedance : 0Ω, when the read amplifier output voltage is amplified 100 times and voltage passed though EN a a a a a b a a a b b a a LPF (low pass filter of cutoff frequency 15MHz) is VN [Vrms], EN= VN 100 • AV • 15 × 106 Typ. Max. Unit 0.55 0.7 nV Hz Test point : V5 In-phase input voltage SG2 : 100mVp-p, 5MHz When the Read amplifier output is VCM Common mode 10 CMRR b a a a d b a a a b b a [mVp-p], rejection ratio CMRR=20 log 100 VCM +20 log AV 50 dB 11 Power Supply rejection ratio Test point : V4 Ripple voltage SG3 : 100mVp-p, 5MHz When the Read amplifier output is VP PSRR a a a a a b b a a b b a [mVp-p], PSRR=20 log 100 VP +20 log 50 dB 12 Channel separation CS Test point : V4 Selected head input voltage : 0mVP-P Unselected head input voltage SG1 : 100mVp-p, 5MHz a b a a c b a a a b b a When the Read amplifier output is VCS [mVp-p], CS=20 log 100 VCS +20 log AV 50 dB Test point : V4 Read data VOFFR=V2–V3 13 output offset VOFFR b a a a a b a a a a b a Test point : V2, V3 voltage for Read –200 200 mV —6— CXA1940N Unless otherwise specified, VCC=5V, Ta=25°C, fWD (Write data frequency)=5MHz, IW=20mA, LH (Head inductance)=1µH, RH (Head DC resistance value)=30Ω Refer to Fig. 2 to Fig. 4 No. Item SymMeasurement conditions Min. Typ. Max. Unit bol Vp-p VSW Differential voltage between HX pin and HY pin 4.4 5.2 at switching of Write current 280 1000 kHz FWUS FWUS is the max. Write data frequency when Pin 11 turns “High” in Write mode. 0.6 µs 14 Head differential voltage amplitude 15 Write unsafe detection max. frequency 16-1 Mode switching time TRW TRW is the time required for Write current to turn Read to Write to 90% after Pin 19 changes from “High” to “Low”. 16-2 Mode switching time TWR TWR is the time required for either Write current Write to Read to decrease to 10% or for the Read amplifier output∗ to turn to 90% after Pin 19 changes from “Low” to “High”. 17-1 Mode switching time TSA1 TSA1 is the time required for Pin 11 to turn “High” safe to unsafe after the last transition of Write data when Write data is stopped in Write mode. 17-2 Mode switching time TSA2 TSA2 is the time required for Pin 11 to turn “Low” unsafe to safe after the first transition of Write in Write mode. 18 Mode switching time TPR T PR is the time required for Read amplifier Power save to Read output to turn to 90% after Pin 20 changes from “High” to “Low”. 19 Head switching time TH TH is the time required for the Read amplifier output∗ to reach 90% when the selected head switched in Read mode. 20 Write current TPD T PD is the time required for Write current to propagation delay reach 90% after the Write data falling edge. time LH=0µH, RH=0Ω 21 Write current rise/fall TR/TF TR is the time required for Write current to reach time 90% from 10%; TF is the same time required to reach 10% from 90%. LH=0µH, RH=0Ω ∗Read amplifier output 100mVp-p 10MHz 0.6 µs 3 7 11 µs 1.0 1.0 µs µs 0.6 µs 30 ns 5 10 ns —7— CXA1940N Test Circuit 1 ×100 AMP 1k 1k VCC 5V SG3 VCC 5V LPF V V5 to 15MHz ×1 AMP A I4 b a S7 5V 0V 500kHz PG 1µ V V4 1µ V3 1µ V2 5V ab S12 ab S11 V ba V ba ab S9 ab S8 PG1 abc S6 5.1k V1 V S10 8.2k A I8 20 A I7 19 18 A I6 17 16 15 A I5 14 13 A I3 12 A I2 11 1 2 S1 ab 3 ab 4 S2 ab S5 5 ab 6 S3 ab 7 ab 8 S4 ab 9 ab 10 ab cd e a I1 33 bc d e 0.1µ SG2 A 0.1µ 0.1µ Fig. 1 SG1 Test Circuit 2 ×1 AMP 1k 1k 5V 1µ PG PG 1µ 1µ PG 5V PG 8.2k 18 17 16 15 5.1k 11 0V 20 19 14 13 12 1 2 3 4 5 6 7 8 9 10 1µH 1µH 1µH 1µH Fig. 2 Note) Write current is measured with current probe. Use an oscilloscope to test items related to time. —8— CXA1940N Timing Chart 1 WDI R/W 50% 50% PS TRW TWR 50% 90% IWX IWY 10% 90% 10% TWR TPR RDX RDY 90% 90% Fig. 3 Timing Chart 2 WDI 50% 50% TPD 90% IWX IWY 10% TR 10% TF TSA1 90% 90% WUS TSA2 50% 50% Fig. 4 —9— CXA1940N Description Functions Read amplifier This is a low noise amplifier amplifying the signals from the head and is an emitter follower output. It outputs to RDX and RDY pins differentially. The head X side and RDX pin, the head Y side and RDY pin have the same polarity. RDX, RDY outputs become high impedance in write mode (when these outputs is AC coupled to the load). Write circuit Write data which is input to WDI pin passes through a T flip-flop and frequency is divided into 1/2. It then drives the Write switch circuit and flows Write current to the head. Write data is triggered where from “High” to “Low” and Write current is switched. Write current flows from X side when Read changes to Write. Mode control Modes are set as shown in Table 1 using R/W and PS pins. R/W L H H PS L L H Mode Write Read Power save Table 1. Mode selection Head selection Heads are selected as shown in Table 2 using HS0 and HS1 pins. HS0 L H L H HS1 L L H H Head 0 1 2 3 Table 2. Head selection —10— CXA1940N Write unsafe detection circuit Abnormal Write mode is detected. In normal Write mode, WUS output turns to “Low” and in the following other conditions, WUS output turns to “High”. • • • • • • Head input is open. Head input is shorted to GND. Write data frequency is abnormally low. No write current In read In power save Power supply ON/OFF detection VCC is monitored to avoid incorrecting Write. Recording and Playback functions are inhibited as detected as abnormal when VCC decreases below the power supply ON/OFF detector threshold voltage (VTH). When VCC is higher than VTH, the above inhibition is released. —11— CXA1940N Application Circuit +5V PULSE DETECTOR RW 8.2k 20 19 18 17 16 15 1µ 5.1k 14 13 12 11 1 2 LH 1µH 3 4 LH 1µH 5 6 LH 1µH 7 8 LH 1µH 9 10 NC Application circuits shown are typical examples illustrating the operation of the devices. Sony cannot assume responsibility for any problems arising out of the use of these circuits or for any infringement of third party and other right due to same. —12— CXA1940N Notes on operation • This device handles high frequency and high gain signals. Please note the following; ♦ Connect VCC decoupling capacitor of approximately 1000pF near the device. ♦ Make the GND area as large as possible. • When using as 2-channel, short-circuit the X and Y sides of unused head pins or leave them open. • Write data pulse width Set the pulse width to 10ns or more at 1.5V to prevent misoperation. • The WC pin is a constant voltage pin. When noise affects this pin, it creates noise in Write current. Therefore, locate RW as close to the device as possible . • Write unsafe detection circuit This circuit uses the voltage waveforms of the head pins for detection. Wave form of write data T1 Voltage waveform of head pins (HX, HY) VFB 1.5V VTH=2V VTH GND ♦ The condition of T1 >10ns must be met for the WUS detection circuit to operate properly. ♦ VFB must be more than 2V. When VFB < 2V, it is possible that Write unsafe detection maximum frequency becomes more than 1MHz. ♦ The normal operating area of write unsafe detection circuit is changed by head inductance, head DC resistance, write current and other. —13— CXA1940N Application Notes Use the following characteristics for reference. Symbol Differential output capacitance CO Item Differential output resistance Differential input capacitance Read mode Differential input resistance Output resistance Unselected head differential current in Write mode Write current symmetry ∗TAS=T1—T2 RO CI RI Conditions Between head input pins 230 Between head input pins f=5MHz Min. VCC=5V, Ta=25°C Typ. Max. 15 310 14 0.7 1.4 40 60 0.2 –1 1 390 20 Unit pF Ω pF kΩ Ω mAp-p ns Write mode RRD RDX or RDY, f=5MHz IUS LH=1µH, RH=30Ω Iw=20mA TAS∗ LH=0µH, RH=0Ω Iw=20mA IWX+IWY 50% T1 50% T2 50% Setting of Write current Write current can be set with resistor Rw (kΩ) at Pin 18. Iw=K/Rw (mA) Refer to Fig. 5 and 6. WC 18 RW Fig.5 Write current vs. RW Fig. 6 Write current setting constant vs Write current 148 20 K=Rw • IW 10 Write current setting constant K 146 IW -Write current (mA) 144 142 5 140 5 10 RW ( KΩ) 20 30 5 10 15 20 Write current IW ( mA) —14— CXA1940N Fig.7 Normalized write current vs Supply voltage Fig. 8 Normalized write current vs Ambient temperature VCC=5V 1.01 Ta=25°C 1.01 IW /IW ( Ta=25°C) 4 IW /IW ( VCC=5V) 1.00 1.00 0.99 0.99 0.98 5 6 Supply voltage VCC ( V) 7 –25 0 25 50 Ambient temperature Ta (°C) 75 Fig. 9 Normalized read amplifier voltage gain vs Supply voltage 1.02 Ta=25°C 1.01 1.01 Fig. 10 Normalized read amplifier voltage gain vs Ambient temperature VCC=5V AV/AV ( Ta=25°C) AV/AV ( VCC=5V) 1.00 1.00 0.99 0.99 0.98 4 5 6 Supply voltage VCC ( V) 7 –25 0 25 50 Ambient temperature Ta (°C) 75 Fig. 11 Power supply ON/OFF detector threshold voltage vs Ambient temperature 4.0 Power supply ON/OFF Detector Threshold Voltage (V) OFF→ON 3.9 ON→OFF 3.8 –25 0 25 50 Ambient temperature Ta (°C) 75 —15— CXA1940N Package Outline Unit : mm 20PIN SSOP (PLASTIC) ∗6.5 ± 0.1 + 0.2 1.25 – 0.1 0.1 20 11 A ∗4.4 ± 0.1 1 + 0.1 0.22 – 0.05 10 0.65 ± 0.12 + 0.05 0.15 – 0.02 0.1 ± 0.1 0° to 10° DETAIL A NOTE: Dimension “∗” does not include mold protrusion. PACKAGE STRUCTURE PACKAGE MATERIAL SONY CODE EIAJ CODE JEDEC CODE SSOP-20P-L01 SSOP020-P-0044 LEAD TREATMENT LEAD MATERIAL PACKAGE WEIGHT EPOXY RESIN SOLDER / PALLADIUM PLATING COPPER / 42 ALLOY 0.1g —16— 0.5 ± 0.2 6.4 ± 0.2